Crystalline metallic Au nanoparticle-loaded α-Bi2O3 microrods for improved photocatalysis

Abstract

Crystalline metallic Au nanoparticles were loaded on α-Bi₂O₃ microrods (Au/α-Bi₂O₃) using an Au deposition–precipitation method. The prepared samples were characterized by scanning electron and transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and UV-vis diffuse reflectance spectroscopy. Upon visible light irradiation, the Au/α-Bi₂O₃ exhibits much higher photocatalytic activities than the pure α-Bi₂O₃ for the degradation of Rhodamine B and 2,4-dichlorophenol in aqueous solution. The role of the Au and the paths of electron transport in the photocatalysis of the Au/α-Bi₂O₃ were investigated and discussed in detail based on the analysis of the photo-generated hydroxyl radicals (˙OH) and hydrogen peroxide (H₂O₂) in the visible light irradiated suspension of pure α-Bi₂O₃ and Au/α-Bi₂O₃. The result reveals that the Au loaded on α-Bi₂O₃ plays a critical role in the separation of the electron and hole pairs by accumulating the electrons from the excited α-Bi₂O₃, which is responsible for the enhanced photocatalytic activity.